The present invention relates to a display apparatus for displaying an image and, more particularly, to a display apparatus for displaying a stereoscopic image for industrial, domestic, and medical uses.
In a conventional stereoscopic display system, a viewer wears glasses for separating right and left images from each other whereby right and left eyes of the viewer can selectively see right and left screen images, respectively, which are displayed on an image field in a time-division fashion. In another conventional technique, a lenticular plate is attached to an image field so that the lenticular plate can separate right and left images from each other and thus right and left eyes of the viewer can selectively see right and left screen images, respectively.
FIG. 1 illustrates an example of the configuration of the above-described conventional stereoscopic-image display system, which includes glasses 60 capable of separating right and left images from each other, liquid crystal shutters 61a and 61b, a synchronous circuit 62, and color CRT 63 serving as an image display device.
The above first example of a stereoscopic-image display system having such a configuration operates as follows. The color CRT 63 displays stereoscopic images wherein screen images for right and left eyes are displayed alternately in a time-division fashion. Under the control of the synchronous circuit 62, the liquid crystal shutter 61a of the glasses 60 is opened and thus become transparent only when screen images for the right eye are displayed, and the liquid crystal shutter 61b is opened and become transparent only when screen images for the left eye are displayed. As a result, a viewer wearing the glasses 60 can observe screen images for the right eye with his or her right eye, and screen images for the left eye with the left eye. In this way, stereoscopic vision is provided.
FIG. 2 illustrates the configuration of the second example of a conventional stereoscopic-image display system, which includes a lenticular plate 71 having a large number of cylindrical lenses touching each other in parallel and a color CRT 72 serving as an image display device.
This second example of stereoscopic-image display system having such a configuration operates as follows. The color CRT 72 simultaneously displays both screen images for right and left eyes such that screen images for right and left eyes having radius-width of each cylindrical lens (slit-shaped) are displayed alternately on arbitrary positions in each cylindrical lens of the lenticular plate 71. The right eye of a viewer sees only the screen images for the right eye displayed on the above-described slit-shaped zones through each cylindrical lens of the lenticular plate 71, and the left eye sees only the screen images for the left eye displayed on the slit-shaped zones, whereby stereoscopic vision is obtained.
In the first example of the conventional stereoscopic-image display system, however, a viewer has to wear troublesome and uncomfortable glasses which separately provide screen images to right and left eyes of the viewer. Another problem in observing stereoscopic images using this technique is flicker due to the switching between the screen images for right and left eyes.
In the second example of the conventional stereoscopic-image display system, since a stripe-shaped stereoscopic image is observed via cylindrical lenses, stereoscopic vision can be obtained only when a viewer is in a limited narrow area. If the viewer moves, degradation occurs in the image. Besides, many viewers at various positions can not observe an image at the same time. Furthermore, image processing is necessary to provide a stripe-shaped image, thus requiring an expensive apparatus.
In medical applications, when an endoscopic operation is done, an operator usually observes a plane image of the inside of a patient's abdominal cavity displayed on a monitor via an endoscope. In which case, the monitored image of the inside of the abdominal cavity has little characteristic features because the entire abdominal cavity is displayed in a single color, thus it is difficult to give perspective vision. This causes a long operation time, and causes heavy loads to both operator and patient. As described above, when a conventional stereoscopic-image display system of the above-described first or second type is used in the operation, there are serious problems in practical use such as uncomfortable glasses for separating right and left images, flicker of an image, and limitation in movement of a viewer.